The seismic design categories and corresponding short-period design spectral response accelerations, SDS shown in Figure R301.2(2) are based on soil Site Class D, as defined in Section 1613.3.2 of the International Building Code. If soil conditions are other than Site Class D, the short-period design spectral response accelerations, SDS, for a site can be determined in accordance with Section 1613.3 of the International Building Code. The value of SDS determined in accordance with Section 1613.3 of the International Building Code is permitted to be used to set the seismic design category in accordance with Table R301.2.2.1.1, and to interpolate between values in Tables R602.10.3(3), R603.9.2(1) and other seismic design requirements of this code.
TABLE R301.2.2.1.1 SEISMIC DESIGN CATEGORY DETERMINATION
TABLE R301.2.2.1.1 SEISMIC DESIGN CATEGORY DETERMINATION
| CALCULATED SDS | SEISMIC DESIGN CATEGORY |
| SDS ≤ 0.17g | A |
| 0.17g < SDS ≤ 0.33g | B |
| 0.33g < SDS ≤ 0.50g | C |
| 0.50g < SDS ≤ 0.67g | D0 |
| 0.67g < SDS ≤ 0.83g | D1 |
| 0.83g < SDS ≤ 1.25g | D2 |
| 1.25g < SDS | E |
Buildings located in Seismic Design Category E in accordance with Figure R301.2(2) are permitted to be reclassified as being in Seismic Design Category D2 provided that one of the following is done:
1. A more detailed evaluation of the seismic design category is made in accordance with the provisions and maps of the International Building Code. Buildings located in Seismic Design Category E in accordance with Table R301.2.2.1.1, but located in Seismic Design Category D in accordance with the International Building Code, shall be permitted to be designed using the Seismic Design Category D2 requirements of this code.
2. Buildings located in Seismic Design Category E that conform to the following additional restrictions are permitted to be constructed in accordance with the provisions for Seismic Design Category D2 of this code:
2.1. All exterior shear wall lines or braced wall panels are in one plane vertically from the foundation to the uppermost story.
2.2. Floors shall not cantilever past the exterior walls.
2.3. The building is within the requirements of Section R301.2.2.2.5 for being considered as regular.
1. A more detailed evaluation of the seismic design category is made in accordance with the provisions and maps of the International Building Code. Buildings located in Seismic Design Category E in accordance with Table R301.2.2.1.1, but located in Seismic Design Category D in accordance with the International Building Code, shall be permitted to be designed using the Seismic Design Category D2 requirements of this code.
2. Buildings located in Seismic Design Category E that conform to the following additional restrictions are permitted to be constructed in accordance with the provisions for Seismic Design Category D2 of this code:
2.1. All exterior shear wall lines or braced wall panels are in one plane vertically from the foundation to the uppermost story.
2.2. Floors shall not cantilever past the exterior walls.
2.3. The building is within the requirements of Section R301.2.2.2.5 for being considered as regular.